Rats can't usually see infrared light, but they have
"touched" it in a Duke University lab. The rats sensed the light as a
sensation of touch after Duke neurobiologist Miguel Nicolelis and his team
fitted the animals with an infrared detector wired to electrodes implanted in
the part of the mammalian brain that processes information related to the sense
One of the main flaws of current human, brain-controlled
prosthetics is that patients cannot sense the texture of what they touch,
Nicolelis said. His goal is to give quadriplegics not only the ability to move
their limbs again, but also to sense the texture of objects placed in their
hands or experience the nuances of the terrain under their feet.
How the study will
His lab studies how to connect brain cells with external
electrodes for brain-machine interfaces and neural prosthetics in human
patients and non-human primates, giving them the ability to control limbs, both
real and virtual, using only their minds. He and his team have shown that
monkeys, without moving any part of their real bodies, could use their
electrical brain activity to guide the virtual hands of an avatar to touch
virtual objects and recognise their simulated textures.
His latest study, published in Nature Communications, shows that the rats' cortexes respond
both to the simulated sense of touch created by the infrared light sensors and
to whisker touch, as if the cortex is dividing itself evenly so that the brain
cells process both types of information.
This plasticity of the brain counters the current
"optogenetic" approach to brain stimulation, which suggests that a
particular neuronal cell type should be stimulated to generate a desired
neurological function. Instead, stimulating a broader range of cell types might
help a cortical region adapt to new sensory sources, Nicolelis said.
His team recently documented the firing patterns of nearly
2,000 individual, interconnected neurons in monkeys. Recording the electrical
activity from thousands of neurons at once is important for improving the
accuracy and performance of neuroprosthetic devices, he said.
Infrared sensing to
be built in
This brain-machine interface work is all part of an
international effort called the Walk Again Project to build a whole-body
exoskeleton that could help paralysed people regain motor and sensory abilities
using brain activity to control the apparatus. He and his collaborators expect
to first use the exoskeleton in the opening ceremony of the FIFA Soccer World
Cup in June 2014.
Nicolelis said infrared sensing might be built into such an
exoskeleton so patients wearing the suit could have sensory information about
where their limbs are and how objects feel when they touch them.
Nicolelis is a professor of neurobiology, biomedical
engineering and psychology and neuroscience at Duke University. He is also
founder of Duke's Center for Neuroengineering. He earned his M.D. from the
University of Sao Paulo Medical School and his Ph.D. from the Institute of
Biomedical Science at the University of Sao Paulo, Brazil.